Bending apparatus for bending metal stock flatwise into curvilinear form



A. YURKA, JR BENDING APPARATUS FOR BENDING METAL STOCK FLATWISE INTO CURVILINEAR FORM 4 Sheets-Sheet 1 April 5, 1960 Filed April l0, 1958 :inventor ,406057 Yue/KA Je.

2,931,41 7 STOCK April 5, 1960 A. YURKA, JR

BENDING APPARATUS FOR BENDING METAL FLATWISE INTO CURVILINEAR FORM 4 Sheets-Sheet 2 Filed April l0, 1958 Gtlorneg April 5, 1960 A. YURKA, JR 2,931,417

BRNDING APPARATUS FoR BENDING METAL sTocK FLATwIsE: mo cuRvILINEAR FORM 4 Sheets-Sheet 3 Filed April 10, 1958 Bnnentor Aaa/5T )faz/(A 7E.

April 5, 1960 A. YURKA, JR 2,931,417

BENDING APPARATUS FOR BENDING METAL sTocx FLATWISE INT0 CURVILINEAR FORM Filed April 1o, 195s 4 Sheets-Sheet 4 FZ7 /f gg nventor 6 ,406057 Yue/A fe.

h Gttorueg United States Patent BENDlNG APPARATUS FR BENDENG METAL STCK HATWSE ENT@ CURVELNER EGEM August Yurlra, Jr., Cleveland Heights, Ohio, assigner te yril Bath Company, Solon, Ghia, a corporation o o Application April 1li, 1958, Serial No. 727,565 5 Claims. (Cl. E53-54) This invention relates to an apparatus for bending etal stock atwise into curvilinear form and particularly to an apparatus in which the basic principles of a three roll bender are utilized, but are supplemented and modied by cooperable principles such that new operations can be performed which cannot be performed by the conventional three roll bender.

`For the purposes of illustration, the invention is disclosed herein as embodied in a wipe forming machine of the general character disclosed in US. patent to Cyril l. Bath, No. 2,514,830, issued July ll, 1950, for which it is particularly adapted, its embodiment in other and specialized types of apparatus being readily apparent from the illustrative example.

ln the bending of stock with prior conventional three roll benders, one rotatably driven roll serves as a main side face die or forming roll against the periphery of which one face of the stock to be bent is disposed in taugency while the stock is driven endwise and bent into curvilinear form. Two bending rolls, spaced circumferentially of the forming roll from each other and spaced radially from the forming roll, with their axes parallel to the axis of the forming roll, are applied tangentially to the opposite face of the stock for bending the stock about the point of tangency of the stock and forming roll. ln the bending position, the line of taugency of the stock with the forming roll is between the lines of taugency of the stock with the two bending rolls. The latter lines of tangency are spaced from the periphery of the forming roll so that, except in one specific case, the stocl; is spaced from the periphery of the forming roll at its lines of taugency with the bending rolls. These 'lines are sufficiently close to the periphery of the forming roll so that they dene a common plane which is always closer to the axis of the forming roll than is a parallel plane through the line of taugency of the stock and forming roll.

rlhus, the bending rolls impart a bend to the stock lwhich is concave toward the forming roll. By adjusting the position of the bending rolls relative to the forming roll, the degree of curvature is controlled. This prior structure, when adjusted, remains lixed in the adjusted position during the complete bending operation.

However, these prior benders have two serious disadvantages. One disadvantage is that the bending is done without any direct forming pressure on the outer surface of the stock at the convex side of the bend with the result that the metal does not have the proper ow for reducing or substantially eliminating, spring back.

The other, and greater, disadvantage is that it cannot Vbend either the leading end portion or the trailing end portion of the stock which is passed through it. This failure is caused by the fact that the leading end portion of the stock, of a length from the instantaneous line of taugency of the stock with forming roll to a point just beyond the trailing bending roll in the direction -of travel, is positioned beyond the instantaneous line of taugency of the stock with the forming roll when the er"ice stock is initially installed for bending. Consequently, the entire free leading end portion must swung bodily toward the forming roll about the instantaneous line of taugency of its relatively trailing end which was tangent to the forming roll when the stock was installed in the apparatus, and bent only at and adjacent that line. While this instantaneous line of taugency between the forming roll and the trailing end of the straight leading portion of the stock migrates a small amount toward the trailing bending roll, it remains always a substantial distance from the trailing bending roll. Hence, the length of the leading portion, from the trailing bending roll to the point of nearest approach thereto of the instantaneous line of taugency of the stock with the forming roll, remain straight. It is not forced to bend across the instantaneous line of tangency as a fulcrum at successive minute increments along its length, progressively from its leading edge to said point of nearest approach, as must all points along the stock if the curve is to be continuous.

The remainder of the length of the stock is incrementally bent across the instantaneous line of taugency progressively from the trailing end of the leading portion to the leading end of the trailing portion which is that between the trailing end of the stock and instantaneous line of taugency when the trailing end of the stock is under the leading bending roll. t/'hen the trailing end of the stoel; passes the leading bending roll, it is free to, and does, spring outwardly from the forming roll and thus remains straight and adjusts itself so as to pass the instantaneous line of taugency without bending thereacross as a fulcrum.

Yet, to impart a continuous bend, it is necessary that each increment of the length of the stock be bent as it passes over the instantaneous line of taugency of the stock 'ith the forming roll. This incremental bending for the entire stock length necessitates that (a) until the entire length of the stock has been progressively, incrementally bent, pressure be applied at at least two locations spaced from each other endwise of the stoel; at the face opposite that which engages the forming die at the instantaneous line of tangency, and (b) one of these points of pressure be spaced endwise of the stock from the instantaneous line of taugency and the other be either spaced endwise of the stock from said line in the opposite direction from the rst point or be at the instantaneous line of taugency.

ln accordance with the present invention, both of the disadvantages mentioned are eliminated and progressive incremental bending of the entire length of the portion of stock to be curved is effected so that the stock may be bent into a continuous curve entirely to its ends at preselected radii of curvature.

Furthermore, in accordance with the present invention, compression forces are applied to the outer surface of the stock exposed away from the forming roll or die at the instantaneous line of taugency so that the metal at this surface is compressed and therefore is caused to flow and elongate more effectively, thus imparting a better set to the stock, improving the metallurgical properties of the curved part, and reducing the spring back after the stock is released from the rolls.

Additional advantages of the present structure are that means are provided` for infinite changes in the relative positions of the forming die or roll and the bending rolls during the bending operation while, at the same time, maintaining the stock firmly against the forming roll at the point of taugency, and that, with slight adjustment of the positions of the bending rolls relative to the instantaneous line of taugency of the stock with the forming roll, a wide range of radii of curvature can be obtained so that the forming roll can be used for forming a large number of parts of dderent diameters and parts having different radii of curvature at different portions, respecbe supplied, selectively, f the opposite side of the tion with the forming roll or die and arranging the pressure roll, along the path of travel of the stock, between the two bending rolls and in a position to engage the stock, under pressure, at the instantaneous line of tangency of the stoel: with the formingroll. v

The advantages resulting from the addition yof the pressure roll are that, since the stock is held, during vthe bending operation, against the forming Yroll at the instantaneous line of tangency of the stock with the forming roll by means of a pressure roller, each .increment of length of the stock is constrained to bend across the line of tangency as a fulcrum, progressively entirely from the leading end to the trailing 'end of the .length of stock to be bent, thus eliminating Vstraight leading and trailingfend portions at the opposite ends of the stock.

A secondary advantage is that the Vmetal'iscompressed and caused to now by the compressive iiow at the instantaneous line of contact as it is being bent thereacross, so that springback is eliminated and better quality Vin the finished article results'.

Various other objects and advantages of the present in= vention will become apparent from the following description, wherein reference is made to the drawings in which:

Figs. l and 2 are a top plan View and a side elevation, respectively, of a wipe forming machine embodying the principles of the present invention;

Fig. 3 isV an Yenlarged fragmentary plan View of part of the structure illustrated in Figs. l and 2, showing in greater detail the cooperable relation of the rolls;

Fig. 4 is a side elevation of the structure illustrated in Fig. 3;

Fig. 5 is a fragmentary front elevation of a modified form of the structure;

Fig. 6 is a vertical 6 6 in Figs. 5 and 7;

Fig. 7 is a horizontal 7-7 in Figs. 5 and 6;

Fig. 8 is a fragmentary front elevation of a modiiied arrangement of the pressure and bending rolls of the present invention, and mounting therefor, parts thereof being shown in section;

Fig.` 9 9 in Fig'. 8, parts thereof being shown in elevation;

Fig. l0 is a vertical sectional View taken on the line S10-i0 in Fig. 8, parts thereof being shown in elevation;

Fig. l1 is a front elevation illustrating another modication of the invention, part thereof being shown in section for clearness in illustration;

Fig. V12 isV a vertical sectional View taken on the line 12-12 in Fig. l1; and

Fig. 13 is a horizontal sectional view taken on the. line 13*13 in Figs. ll and l2, .part thereof being shown in section for clearness in illustration.

Referring rst to Figs. l through 4, the invention is shown embodied in a rotary wipe former of the type described in the above identied patent and which comsectional view takenY on theV line sectional view taken on the line prises a base l on which is rotatably mounted a turntableV 2 which supports a main curvilinear side face die or forming roll 3, preferably coaxial with the turntable 2. Mounted on the frame l is a reversible hydraulic piston and cylinder assemblage, indicated generally at 4, and comprising a cylinder 5 in which is operable a piston 6 having a rod 7. Mounted in a suitable guide 8 on the base 1 is a slide 9 which is slidable. parallel to the axis of the piston toward and away from the axis of the turntalige 2 in a plane parallel to the planeV of the top of the a e. Y

Hydraulic pressure fluid is supplied from a suitable sump pump 1G driven by a motor 11 to a reversing ,K and cut-od valve 12 by virtue of which pressure fluid can 9 is a horizontal sectional View taken on the line to either side of the piston and piston connected -to a sump .13 which, in turn, is connected to the pump 1t). The structure thus described is a wipe'former on the forward end of the slide 9 of which he wipe forming shoe customarily is mounted. Y

For the present purpose, however, instead of the conventional wipe shoe, a pair of bending rolls and, in addition, a pressure roll are mounted on the slide.V On the forward end ofthe slide 9, and rigid therewith, is a generally upright pedestal 14 by which the pressure roll and the bending rolls are supported for movement by the assemblage 4, lIn the form illustrated, a pressure roll l5 and bending rolls i6 are provided'. A suitable head frame, comprising top and bottom plates 18 and 19 secured in vertically spaced parallel relation :to each other on a plate Ztl, supports the pressureand bending rolls. This structure is arranged to be connected in xed position on a suitable supporting member '21 having a rearwardly extending tongue portion 22 which is received between yoke arms 23 and is pivotally connected thereto for vertical swinging movement by a suitable pivot 24. The yoke arms, in turn, are secured to a supportingplate 25 which is adapted to be connected to the pedestal i4 and keyed into position thereon by a suitable key 25 engaging a keyway 27 in the plate 2S. An extra keyway 23, offset from the keyway 27, is provided so that the member can be shifted transversely on the support or pedestal i4 if so desired and keyed in the new position.

The bending rollsY 16 are mounted Vbetween the plates 13 and ll9 and have hub portions 29 which are rotatable inV suitable sleeve bearings in the plates 18 and 19 for rotatably supporting the rolls for rotationY independently of each other.

The pressure roll i5, in turn, is mounted in upper and lower plates 30 which are secured to the upright plate 20 by suitable bolts 31 by which the plates 3l) are drawn firmly into position against the forward face of the plate 2Q and are held lixedly in such position. t

lt is desirable'that the bending rolls 16 beV adjustable forwardly and rearwardly with respect to the roll 15 so as to change the radius of curvature of the stock being formed, as will later be described, and for this purpose the Supporting plates 30 for the roll 15 are adjustable forwardly and rearwardly Yof the platetZtl by the introduction of suitable shims 32 between the forward face of the plate Z0 and the ends of the plates 30 adjacent to it.

In order to yieldably support the rolls 15 and 16 in an upright position, a suitable spring 34 is interposed between the tongue portion 21 and the supporting plate 25, this spring being of suiiicient strength to counterbalance the overhanging weight of the roll and other `parts supported by the pivot 24 with respect to the axis of the pivot 24 and thus retain the rolls with their axes in substantially upright position while allowing them to rock about the pivot as a group to adjust themselves to different variations in the stock.

in all operating positions of the rolls l5 andtld, the roll 1S is arranged to be tangential to the stock at au instantaneous line of tangency of the stock with the forming roll 3. In the illustration, the roll i5' is in this tangential position, with its axis in an upright plane dened by the axis of the piston and cylinder assemblage 4 and' the axis of the table 3.

"The plane dened by the instantaneous lines of tangency of the bending rolls 15 with the stock is always nearer to the axis of the forming roll 3 than is a plane parallel thereto through the nstantaneous'line of tangency of the pressure roll l5 and the stock, so as to bend the stock in a direction to make yit concave toward the forming roll V3. The lines of tangency of the bending .rolls 1,6 and the stock are always sufficiently spaced from the peripheral forming face of the forming roll 3 so that the stock is spaced from the peripheral formingv face at these lines of tangency and for a considerable distance therefrom toward the instantaneous line of tangency of the stock and the pressure roll 15.

As mentioned, the invention is ated in a wipe former such as described in the above identified patent, in which case the relative rotation of the forming roll 3 and the rolls 15 and 16 is obtained by rotation of the table. However, if desired, the table may be held stationary and the frame swung thereabout to efiect the same relative rotation.

Let it be assumed that the table in Fig. 3 is rotating in a counterclockwise direction relative to the set of rollers. In order to form a length of stock S by bending it atwise, the length of stock S is introduced between the leading bending roll 16 and the peripheral surface of the forming roll 3, its free end being disposed so that the leading edge of the stock is at the point for engagement by the roll 15. Power is then applied to the piston and cylinder assemblage so as to force the pressure roller rmly against the leading edge of the stock, thus pressing it iirmly against the forming roll 3 at the instantaneous line of tangency between the forming roll and stock. With the forward end of the stock thus held in position and the bending rolls disposed with their instantaneous lines of tangency in a plane nearer the axis of the forming roll than the instantaneous line of tangency of the stock and forming roll 3, the instantaneous line of tangency of the stock and forming die cannot migrate toward the leading bending roll 16 and consequently an increment of bend is imparted substantially at the free end over its line of tangency of the forming roll 3 as a fulcrum.

The forming roll is then rotated and continues progressive incremental bending of the stock as it passes the instantaneous line of tangency with the forming roll 3. The stock is driven endwise by the forming roll 3 and its leading edge passes between the forming roll 3 and the trailing bending roll where it is given additional bending pressure, and continues until its trailing edge reaches the leading bending roll 16. (1t is to be noted that the rolls 16 in all operating positions are so positioned that they do not press the stock against the die unless the stock is to be made exactly the same curvature as the die.)

When in this position, the trailing end portion of the stock between the leading roll 16 and the line of tangency of the stock with the forming roll 3 is not bent and, as driving is continued, it passes to the line of tangency and between the roll 15 and the roll 3 without bending. Instead of bending, the trailing portion from the instantaneous line of tangency of the stock with the forming roll 3 to the free end, which has just passed from under the leading roll 16, is free to, and does, remain straight and swings about the instantaneous line of tangency between the roll 3 and the stock to a position to pass as a straight piece between the rolls 3 and 15. However, due to the fact that the stock is held against the forming roll 3 by the roller 15, the length of the trailing portion of the stock is constrained to bend by progressive increments across the instantaneous line of tangency as a fulcrum by the trailing bending roll 16 entirely to the trailing end. Thus every increment of length is bent across the instantaneous line of tangency of the stock and forming roll, so that the stock is bent entirely from one end to the other, that is, within such a short distance of the ends that any unbent portion is undetectable. This unbent portion may be from about /z to 1%2 of an inch in length.

Concurrently with the bending, the pressure roll 15 is applied to the stock under quite heavy pressure and thus forms with the forming roll 3 a compression throat which illustrated as incorporcauses a ow of the metal, particularly on the face of the Y stock which is disposed away from the forming roll 3. This ow renders the metal more receptive to the bending stresses and reduces springback.

ln the form described, the degree of bend or radius of curvature depends upon the' distance inwardly, toward the axis of the forming roll, of the plane defined by the instantaneous lines of tangency of the stock with the rolls 16 from a parallel plane through the instantaneous line of tangency of the stock and roll 3 at the roll 15. For example, it has been found that if the roll 3 has a radius of 18 inches, and the plane thus deiined by the lines of contact of the rolls 16 is IAG of an inch nearer to the center of the roll 3 than said parallel plane, a radius of curvature slightly more than the radius of the die is obtained. On the other hand, if the relative position of the rolls 16 with respect to the rolls 3 and 15 are shifted so that the distance between the rst mentioned plane and said parallel plane is a half inch, a radius of curvature of inches is obtained.

There are innumerable variations in radius of curvature which can be obtained by adjustment of the positions of the rolls 3, 15, and 16 relative to each other, regardless of the radius of the roll 3. Accordingly, for most purposes, it is desirable to make the rolls 15 and 16 adjustable and, as heretofore described, if a large number of pieces are to be made with one setting, adjustment can be made in the relative position of the rolls 15 and 16 by adjusting the roll 15 by means of the bolts 31 and shims 32.

However, it is often desirable to make only a few pieces and, therefore, more rapid adjustment of the position of the rolls is required.

For this purpose, a structure such as illustrated in Figs. 5 through 7 is employed. This structure is generally the same as the structure heretofore described, including bending rolls and a forming roll 43. ln this structure, the pressure roll 42 is mounted in a movable housing 44, similar to that in which the roll 15 is mounted. However, instead of being provided with shims and bolts for adjustment, the housing 44, on the side away from the forming roll 43, is provided with suitable cam surfaces 45 which are engaged by movable cams 46. The cams 46 are interposed between a main supporting frame 47 and the rear of the housing 44.

Mounted on the frame 47 is a reversible hydraulic piston and cylinder assemblage 4S to which pressure fluid is supplied by a reversible valve 49 which can be operated to cause the assemblage 48 to move the wedges in opposite directions to selected positions and to lock the wedges hydraulically in the selected positions. Thus, upon operation of the valve 49, the wedges can be operated to move the housing 44 toward the forming roll 43, thus changing the relative distance between the plane through the lines of tangency of the rolls 41 with the stock and a parallel plane through the line of tangency of the stock and roll 43.

Upon supplying iluid pressure to a main cylinder assemblage 50, it urges the pressure roll 42 toward the forming roll 43 and the reaction pressure holds the roll 42 and its housing 44 back in firm contacting relation with the wedges 46.

Referring next to Figs. 8 through 10, another manner of obtaining change in the relative bending positions of the various rolls is by means of spreading the bending rolls apart from each other in a direction endwise of the stock. In this modification, a pressure roll 60 and bending rolls 61 are employed. 'The roll 60 is mounted in a iixed housing 62 which, in turn, is mounted iixedly on a support 63 which is connected to a piston and cylinder assemblage 64, as hereinbefore described, so that the housing 63 is urged toward the forming roll 65. Each bending roll 61 is mounted in a housing 66 which is slidable on suitable guideways 67 toward and away from the pressure roll 60 while maintaining the axes of the rollers 653 and 61 parallel. The housings 66 are slidable along the guideways 67 independently of each other.

Suitable cams 69 are provided between the housing 62 and the housing 66, respectively, and are so arranged that upon vertical movement in opposite directions theyV move their associated rolls 61 relatively toward and awayv Y radius of curvature.

from the Q11 so while maintaining the ses afan of the.

6 1, parallel to a plane tangent tothe forming-roll? 65 at the Vinstantaneous line of tangency, is kept a constant distance from the axisof the forming roll 65 in a direction toward and away from the forming roll 65, the-n movement of the rolls 6l farther outwardly along the plane of their axes from the roll 60 decreases the radius of curvature and movement of the roll 6l inwardly parallel tothe plane of their axes toward the roll 6u decreases Nthe Generally, both rolls 61 are maintained the same distance from the roll 6l). However, it sometimes happens that they are to be atrdilerent distances depending upon the part being formed. Y

For moving the wedges 69, independently operable reversible hydraulic Ypiston and cylinder assemblages 72 and 73ers provided, these assemblies having their piston rods connected to the wedges, respectively. The assemblages are controlled through suitable reversing stop valves 74 and 75, respectively. However, ingeneral use, both thel rollers 6l, when moved to new positions, are moved'the same distance away from the axis of the roll 60. Consequently, means are provided for lockingthe piston rods of the assemblages 72. and 73 together for operation as a unit. A convenient means for thisptupose comprises suitable lugs 78 and 79 on the piston rods which are arranged to be bolted to a suitable tie plate gil. Due to this tie plate, the wedges move equidistantly so that the rolls 6l also move equidistantly at each operation.

It sometimes is desirable to move one bending roll farther away than the other from the pressure roll and, in such an instance, the plate 80 may be removed and eachone of the-piston and cylinder assemblages 7l and 72y can then operate independently so that each places its particular' associated roll at the distance desired.

Again, for some uses, it is desirable to move the bending rolls so that a plane through their axes is closer to the axis ofthe forming die than is a parallel plane through the axis of the pressure roll and, concurrently to move them, endwise of the stock toward and away from the pressure rolls.

i For this purpose, a structure such as shown inFigs. ll through 13 may be employed. In this structure, not only are the bending rolls movable in a direction eudwise of the stocli toward and away from the pressure roll but theV pressure roll is movable in a direction toward and away from the forming roll relative to the bending rolls. This structure provides, therefore, substantially a combination ofthe structure shown in Figs. through 7 with the structure shown in 1Eigs. S through 10.

As illustrated in Figs. ll through 13, the housing 80 is mounted on the pedestalrSl of the wipe forming piston and cylinder assemblage 82 in the manner heretofore described so that it can be urged in'its entirety toward and away from a forming roll 83 by means of the assemblage 52.

In Vthis form, the pressure roll S4 is mounted in a suitable housing 85v which is slidable on guideways $5 toward and awayrfrom the pressure roll and is moved along itsrguideways by means of stationary wedges 87 on the housing S5 and cooperable movable wedges 88, the wedges 37 and 8S corresponding in form and function to the wedges 45 and 46, heretofore described. rlfhe wedges 88 are operated by means of a piston rod 89 of a reversible Vhydraulic piston and cylinder assemblage 90 which may be controlled by the conventional reversible stop valve 9i. Y Also mounted `in the housing tl are the bending rolls 92, each of which is mounted within a suitable housing 93 slidable on slideways 94 toward and away from the housing S5 of the pressure roll. Suitable wedges 96 are operatively interposed between the end walls 9,7 of

the; housing, Si)A and the housing 93, the wedges 96 for aast 70. dies on the carriage for movement ot the pair of bending thosefortheotherof the housings 93.

` These wedges, in turn', are operated by suitable piston y and cylinder assemblages 98, 'each ofwhich may be a I reversible hydraulicpiston andcylinder assemblage which isV operable in either direction or is capable of being locked-in selected positionsr` by means o a suitable reversible and stop valve 99. Thus the movementsof the rolls to dilerent adjusted positions, either inV groups or individually, selectively, can be effected.

' By virtue of these hydraulic arrangements and the control of the valves,V it is apparent that the relative position of theV pressure roll 84 with respect to either or both of the bending rolls ).2l can be changed, as also can the relative' position o,f thea rolls 92 with respect, toY

each other-,both 'inv afdirection toward 'and away from the forming dieanda direction toward and away frotnthef roll 8 MTh'is V'continuation of movements makes possible an infinite vnumbe'ro'f bending eects Aand radii of'curvatuewitlioutlchagesinfhe rolls."V

flu theV form illustrated, the pressure roll and the bendingirolls' are'fsho'wn as cylindrical rolls, as also is the mainforming roll aboutV which the stock is to be formed. lt is assumed` in the illustrations that a flat pieceo stock is to be bent atwisehorizontally so as to form a surface which is curvilinear about an upright axis. However, it sometimes happens that` the stock is not to be formed into a cylindrical body of circular or ellipsoidal cross section but is to be frusto-conical. In such instances, of course, the effect may be obtained by selecting a forming roll and cooperating pressure and bending which are truste-conical in order to fit the surfacerequired, or, due to the pivotal connection between the pedestal and support for the latter rolls, they can be tilted so as to allow for a certain amount of frusto-conical shaping.

If, of course, it is desired to provide articles of circular cross section, then one setting of the rolls is maintained throughout theentire bending operation. On the other hand, if it is desired to provide articles of ellipsoidal times throughout the forming cycle to provide the radius of curvature desired at a particular location. Since the radius of curvature can be changed at different points throughout the operation, as desired, a large number of curvilinear cross sections vare obtainable. v

Having thus described my invention, l claim:

1.111 a metal' forming machine including a table, a side face die thereon and having a curvilinear side face curved about a predetermined axis, a piston and cylinder assemblage adaptedfor connection to a source of yieldable uid pressure and having its axis extending generally toward and away from said side face in a plane normal to the axis of said face, means supporting the table and assemblage for rotation relative to each other about the axis of curvature of said face, a carriage connected tothe assemblage for movement thereby toward and away from the said side face, whereby the carriage may be yieldably urged toward said face when the assemblage is connected to said source, a pair of bending dies mounted on Ythe carriage for movement therewith, said bending dies being spaced apartV circumferentially of the face, a pressure die on the carriage and disposed between the bending dies and positioned with its operating face closer to said side face than the operating faces of the bending dies, and the instantaneous'operating face portions of the bendingdies being ibep/veen the side face and a plane tangent to the side face at the'location of the pressure die. 2. The machine according to claim l wherein supporting means support the pressure die and pair ofy `bending dies relative to the pressure die inv-directions transversely of said rotational axis to preselectedvrelative positions, andpQWer means `onthere arriage are, opperableforY effect: ins widmet/emessi during. Saidv relative rotating @fthecross section, then thel rolls can be shifted at d'itferent dies on the carriage and said side face about said predetermined axis.

3. The structure according to claim 2 wherein the supporting means support the pressure die and a pair of bending dies on the carriage so that the movements of the bending dies and pressure die relative to each other are in directions generally toward and away from said Yside face.

4. The structure according to claim 2 wherein the supporting means support the pressure die and the pair of bending dies on the carriage so that the movements of the bending dies and pressure die relative to each other are in directions generally endwise of the side face;

5. The structure according to claim 2 wherein the supporting means support the pressure die and pair of bending dies on the carriage so that the movements of the bending dies and pressure die relative to each other are in directions generally toward and away from the side face and also generally endwise of the side face independently of their movement toward and away from the side face.

6. The structure according to claim 2 characterized in that the means supporting the bending dies support them for independent movement relative to each other in opposite directions generally endwise of the side face, and the power means are operable to effect said movements of each bending die independently of the lmovement of the other bending die.

References Cited in the le of this patent UNITED STATES PATENTS 

